A panel of Manhattan federal judges says cops must now investigate anonymous 911 calls — before they can investigate the crimes being reported.

The Second Circuit Court of Appeals on Thursday overturned the conviction of an ex-con caught by cops carrying a gun in 2011 as two of the three judges on the panel found the anonymous tips the officers relied on didn’t offer enough “reasonable suspicion” for them to stop and search the defendant Joseph Freeman.

Freeman has a previous rap sheet, and was he found carrying a 9 mm Luger pistol and 10 bullets when stopped by police, according to the indictment.

“The fact that the call was recorded and that the caller’s apparent cell phone number is known does not alter the fact that the identity of the caller is still unknown, leaving no way for the police (or for the reviewing court) to determine her credibility and reputation for honesty — one of the main reasons tips from known sources are afforded greater deference than anonymous ones,” wrote Judge Rosemary Pooler, who, along with Judge Christopher Droney, supported reversing the conviction.

The controversy stems around two anonymous 911 calls made by the same woman on April 27, 2011. She described a man carrying a gun on East Gun Hill Road near a Chase bank, first saying he appeared to be a “Hispanic male” and then a “male black.”

Cops initially walked over to Freeman and put their hands on his elbow, but he shrugged them off and kept walking. One of the cops then put him in a “bear hug” and tripped him to the ground, the panel wrote.

Freeman was then handcuffed and searched, and cops found a gun by his waistband.

“If we accepted the government’s argument that such a simple refusal to comply could create reasonable suspicion where none existed before, we would create a truly paradoxical class of individuals: individuals who cannot be stopped by officers, but who can be stopped if they refuse to stop,” Pooler wrote.

Judge Richard Wesley, the lone dissenter, took a more common sense approach to law enforcement, writing: “This is not a case where a stranger in a muffled voice made a call from a payphone, or where someone dropped off an anonymous note.

“The officers reasonably presumed that the caller could be identified,” Wesley wrote. “They requested that the dispatcher call the tipster back to verify whether she actually saw a gun; the dispatcher in fact did call back on the officer’s request, albeit to no avail.”